Glacier biofilms

If I asked you to draw a glacier, you might draw just a big white blob of ice. But glaciers are really much more complex. To draw them properly, we need to add a lot of details.

Streams run over the surface of glaciers, and sometimes cascade down into the glacier itself where they continue to flow through and underneath it. Pieces of the glacier break off and smash back together as the glacier slowly moves, forming cracks, caverns, and rubble.

Above, the glacier’s surface is pockmarked and dirty from both biological matter (like bird poop and plant pieces) and bits of the Earth (like dust). The dust that accumulates on the glacier is called cryoconite meaning cold dust. It’s made of particles from things like rocks, volcanic eruptions, and power plant emissions. It may have blown onto the glacier from far away, even other continents.

Critically, cryoconite contains microbes.

Pure white snow and ice reflects a lot of light. But dark, sooty cryoconite on a glacier absorbs light, warming the glacier up and making it melt faster than it would otherwise. Small holes form as the cryoconite particles melt the ice around them. Meltwater collects in these holes and makes great habitat for the microbes, which become very active in this water.

Our team studies biofilms and microbial activity in Antarctic cryoconite holes. Biofilms are mats made of microorganisms and extracellular material that stick to each other and a surface (ice in this case). Imagine you’ve poured all the soup out of a bowl and there’s only a thin layer left on the bowl’s surface. If you let that soup sit for a few hours so some of the water evaporated and it got thick and sticky, then its consistency would be like a biofilm’s.

The latest research from our group, and others, suggests that biofilm activity on cryoconite particles starts a cycle of increasing warming and heightened microbial activity.

Melting glaciers release nutrients and other biological materials that were previously trapped in the ice. They also raise sea level. But we can’t take the best steps to protect against the changes that melting glaciers will bring until we know more about what is happening globally, including Antarctica.